Tile or slab made from ceramic or like materials



June 14, 1938. F. W. GRUNDY I TILE OR SLAB MADE FROM CERAMIC OR LIKE MATERIAL Original Filed Feb. 9, 1934 Patented June 14, 1938 UNITED STATES PATENT OFFICE- TILE OR SLAB MADE FROM CERAMIC OR LIKE MATERIALS Francis Wilson Grundy,

Rainford, near St.

Helens, England, assignor to Rainford Potteries Limited, Rainford, England, a British company April 28, 1933 2 Claims.

The present invention relates to new and useful improvements in tiles or slabs of the type shown in my copending application Serial No. 710,551, filed February 9, 1934 of which this is a division. The invention relates more particularly to improvements in tiles or slabs which are made from ceramic earthenware or the like material.

It has been heretofore proposed to provide hollow clay bodies of rectangular or substantially rectangular section with longitudinal grooves to form cleavage lines for the baked body. With the exception of hollow cylindrical bodies or pipes it has hitherto not been possible to obtain a tile or slab the surfaces of which wholly conformed to that of the original clay body as deformation of the sides and surfaces of the body occurred due to the fact that the resultant stresses incident upon drying or baking did not lie wholly within the inner and outer bounding surfaces of the body.

An object of the present invention is to provide a hollow clay body wherein the resultant stresses incident to the drying and baking of the clay body are evenly distributed and lie wholly within its material structure so that the resulting slabs, after the hollow body has been split, have flat and regular surfaces.

A further object of the invention is to provide an extruded hollow polygonal clay body including at least one acute angle which is opposed to an obtuse angle whereby the hollow body can be readily split through the apices of the opposed obtuse and acute angles to form angle slabs having truly flat surfaces.

The above and other objects of the invention will in part be obvious and will be hereinafter more fully pointed out.

The invention relates generally to the provisions of an extruded hollow clay body having at three sides or at most four sides wherein two pairs of the sides are identical and disposed relative to one another so that the hollow clay body is provided with at least one acute angle which is directly opposed to a flat surface or to an obtuse angle. Thus, the hollow clay body is symmetrical about a line intersecting the base or apex of the opposed obtuse, and apex of the acute angle so that it may be split to provide duplicate angular tiles or slabs which have smooth internal and external surfaces. Hitherto it has been found almost impossible to secure perfectly flat slabs in dimensions larger than a few square inches, due to the stresses set up in drying and baking. A tile for facing purposes unless completely flat is useless for aesthetic reasons.

Angular slabs of this character are particu larly desirable as facing bricks or tiles for forming corners or angles of a building where two walls join one another so that there is no mortar or cement seam visible down the corner of the building. These slabs may also be used in the making of window-sills or the like. Where two Walls join one another at an angle of ninety degrees, it is obvious that the angle within each duplicate slab will also be ninety degrees.

The invention is more particularly described with reference to the accompanying drawing in Which:-

Figure 1 shows one form of clay body in perspective.

Figure 2 shows an alternative form of clay body in end perspective View.

Figure 3 is the same body in side perspective View.

In one method of construction, plastic clay is forced by mechanical or hydraulic pressure between a central mandrel of substantially triangular shape in cross-section and an outer die ring having a substantially triangular inner surface in cross-section. The apices of the hollow prismatic body so extruded as shown in the drawing are provided with grooves I.

Any desired grooving, such as 2, may be left on the inside walls. This body is then dried, the drying operation preferably including an initial rapid drying of its surface immediately after extrusion from the die to convert the surface into a porous state, whereby blisters are avoided 'on subsequent baking. The element is then baked to the biscuit stage. It may then be glazed and refired, whereupon the element can be broken up into three separate slabs about the cleavage lines 3 at the bottom of the grooves l, thereby forming three slabs of any desired dimensions.

Where it is desired to form smaller tiles, the grooves, such as 4 may be cut in. the soft clay prior to baking to form extra cleavage lines subsequent to baking.

In another method of construction shown in Figures 2 and 3 plastic clay is forced by mechanical or hydraulic pressure between a central mandrel of prismatic shape in cross-section and an outer die ring of similar shape.

Grooves are preferably formed on the inside of the body as shown at 5, by means of inwardly projecting knives or the like from the die. These grooves are preferably undercut, and as shown at 6 and 1, may be reversed relatively to one another to form a good keying for cement or plaster-work, by which the slabs are attached. It will be found that a roughened edge 8 is formed at one side of these grooves, which further assists this.

It will be found that the body, when baked, will split readily at the apex 9 of the body, and also at the opposing apex l0, thus forming two angular slabs H, 12, of unequal sides, which are particularly suitable for ledges or corner-work in the facing of buildings.

In the manufacture of the body, it is preferably dried after extrusion, the drying operation preferably including an initial rapid drying of its'surface immediately after extrusion from the die to convert the surface into a porous state, whereby blisters are avoided on subsequent baking. The element is then baked to the biscuit stage. It may then be glazed and re-fired, whereupon the element can be broken up into two separate angular slabs about the cleavage apices 9, l0.

Cleavage lines [3 may be formed in the clay prior to baking to facilitate trimming of the slab or to predetermine the width of the finished slab.

From the foregoing description, it will be apparent that minor changes in the details of construction and arrangement of parts may be made Without departing from the scope of the invention as set forth in the appended claims.

I declare that what I claim is:--

1. As a new article of manufacture, a hollow polygonal clay body, the inner and outer surfaces of which are bounded by parallel planes and having acute and obtuse angles directly opposed to one another and including at least two pairs of symmetrical sides.

2. As a new article of manufacture a four-sided hollow clay bodyhaving an acute angle directly opposed to an obtuse angle and being symmetrical about a line intersecting said angles whereby the body may be split through the apices of said angles to form duplicate angular slabs, the inner and outer surfaces of each side of said body lying in parallel planes.

FRANCIS WILSON GRUNDY. 

